Environmental Entomology最新文献

Spiders are dominant predators of agroecosystems, where they must adapt to regular disturbances. Recent studies show that their abundance in crop fields has declined, even at sites not sprayed with agrochemicals. These declines have been attributed mainly to reduced ecosystem complexity, which decreases herbivore populations and consequently limits the prey available to predators. Moreover, spiders, similar to other arthropods, are sensitive to frequent disturbances, such as plowing and mowing. In addition to these well-established drivers, undernourishment of spiders following repeated anthropogenic disturbance may further contribute to declines. We hypothesized that the food preferences of agrobiont spiders change in response to the previously provided diet. As a model, we used females of Heliophanus cupreus (Walckenaer, 1802) and Heliophanus flavipes (Hahn, 1832) (both Araneae: Salticidae), provided with Drosophila melanogaster Meigen, 1830 of various nutrient compositions, and then provided with a protein-rich intraguild prey represented by Dictyna Sundevaal, 1833 spiders and a lipid-rich agricultural pest prey represented by rose-grain aphids Metopolophium dirhodum (Walker, 1849). The prey preferences of the spiders changed in response to the previously provided diet. The lipid-rich diet increased spider survival and led to a preference for agricultural pest prey. In contrast, spiders on standard or protein-rich diets did not prefer agricultural pest or intraguild prey. Agrobiont spiders are able to adjust the spectrum of captured prey to pests dominating the respective crop type. However, the present findings suggest that the nutritional status of spiders may shape their food preferences, with potential, but untested, implications for predator-prey interactions in agroecosystems.

Plant-produced volatiles have been explored as tools for monitoring and managing Halyomorpha halys (Stål), a highly polyphagous pest of orchard and field crops, with hosts such as apple and peach considered as sources of attractants and nonhost essential oils tested as repellents. To identify olfactory stimuli with behavioral relevance to H. halys, volatile organic compounds were collected from hazelnut (Corylus avellana (L.)) trees, a preferred H. halys host, via stir bar sorptive extraction. Extracts were identified by gas chromatography and mass spectroscopy. The physiological effects of 15 host plant volatiles (HPVs) were measured on antennae of H. halys using electroantennographic detection. Halyomorpha halys behavioral responses to the HPVs that elicited consistent antennal responses were assessed In Y-tube olfactometer bioassays, formic acid repelled adult males in a concentration-dependent manner, while trans-2-heptenal produced no clear behavioral effect. Formic acid and trans-2-heptenal both reduced H. halys attraction to hazelnut samples in subsequent single- and dual-choice arena bioassays, with the greatest and longest lasting repellence caused by the highest tested concentration of formic acid. Field experiments indicated no effect of experimental lures containing hazelnut volatiles on H. halys trap captures. The implications of these results for the development of HPV-based strategies for managing H. halys are discussed.

The fungal disease Rapid 'Ōhi'a Death (ROD) has caused extensive mortality in 'ōhi'a (Metrosideros polymorpha Gaudich) forests on Hawai'i Island since the mid-2010s. As the keystone species in native Hawaiian wet forests, the decimation of 'ōhi'a threatens the stability of Hawaiian forest communities. Invasive ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are the primary agents producing ROD inoculum and can directly transmit the pathogens as well. The most common management recommendation for ROD-infected trees is to fell and tarp. However, this is often logistically impractical and does not proactively suppress inoculum production. Alternatively, the semiochemical verbenone has proven effective in repelling ROD-associated beetles from standing 'ōhi'a and may have application in post-felling management. Across two 10-wk field and lab trials, we evaluated two semiochemical formulations, SPLAT Verb (10% verbenone) and SPLAT Beetle Guard (10% verbenone + 10% methyl salicylate), in reducing ambrosia beetle attack, emergence, and frass production when applied to felled ROD-Ceratocystis--infected 'ōhi'a. Verbenone alone significantly reduced beetle attacks and frass production, while verbenone + methyl salicylate also reduced attacks, outperforming verbenone alone by 37% in one trial, and reduced frass production and emergence. Beetle attacks subsided to near zero by week 10, presumably due to bolt desiccation, suggesting a single application may provide sufficient protection for the extent of a felled tree's host-suitability period. Semiochemical repellents may play a pivotal role in the multifaceted management approach needed to control ROD, and these findings validate and expand the emerging body of evidence establishing their efficacy in repelling beetles within the ROD pathosystem.

The wood-boring cerambycid Anoplophora glabripennis (Motschulsky), Asian longhorned beetle, is a highly destructive invasive pest that feeds on healthy hardwoods by tunneling under the bark and then within the sapwood as larvae mature. Larval weight gain and survival can be affected by the nutritional content, moisture content, and physical traits of the available food source. In this study, we experimentally manipulated the larval resource quality by controlling the moisture content of artificial diet (70% and 40% moisture) and by inserting larvae into cut wood of 2 different hosts (sugar maple [Acer saccharum Marshall] and gray birch [Betula populifolia Marshall]). First and/or fifth instars from a Chicago, Illinois laboratory colony were used to follow larval survival, weight, and pupation. Artificial diet moisture content did not affect larvae survival; however, larvae reared on a diet containing 70% moisture weighed more on average than those reared on a diet containing 40% moisture for all time intervals weights were taken. First instars reared in cut gray birch were more likely to survive, grow larger, and molt than first instars reared on cut sugar maple (only one larva survived). The species of cut wood did not have a significant impact on the survival, weight gain, or adult emergence of fifth instars. Our findings suggest that this insect's tolerance of highly variable host quality provides it with ample capacity to survive, disperse, and reproduce even when dietary moisture content is low or declining, as might be expected in trees in the late stages of infestation.

Melanotus communis Gyllenhal (Coleoptera: Elateridae) is a significant wireworm pest of potato and sweetpotato in the southeastern United States. However, the impact of habitat proximity to surrounding crop fields on M. communis abundance remains unclear in this system. More refined risk assessment models to forecast populations as they relate to land use will aid in determining where fields are most vulnerable to damage, enabling more precise management interventions. Between 2022 and 2024, traps baited with M. communis sex pheromone were used to monitor adult male activity for ∼10 wk across 41 locations in North Carolina and Virginia. We combined trap data with remotely sensed land use data to correlate M. communis adult activity to surrounding habitats. The dependent variable used in models was overall mean abundance per location. Abundance was positively associated with the average proportional area of corn over 5 yr. These results are consistent with prior field-scale studies that showed that corn is a preferred host. Model estimates were expanded to understand the frequency of corn surrounding 2,884 potato or sweetpotato fields in 2024. Results showed clear spatial structuring of potato or sweetpotato fields that include corn as an abundant land use type over the prior 5 yr. This study provides a methods framework for expanding traditional landscape studies to communicate infestation risk over broad regions.

When species compete over similar resources, niche partitioning can permit ecologically similar species to coexist. Such coexistence should be a particular challenge for carrion-feeding invertebrates, with the ephemeral nature of carrion leading to intense competition over this nutrient-rich resource. Here we tested whether the carrion niche in four species of coexisting burying beetles (Nicrophorus spp.) is partitioned seasonally or by species size in seven ancient woodlands in the United Kingdom. We fail to replicate the results of previous studies in the UK that found a strict seasonal separation in the activity of competing burying beetle species. Instead, our data support the hypothesis that the niche is partitioned by species size. We present field evidence consistent with the hypothesis that smaller species are less successful at contested carcasses and confirm that sexual dimorphism in head width, a trait likely related to competitive ability, is present in several species of Nicrophorus. We discuss the considerable but as-of-yet unnoticed variation between different geographic populations of Nicrophorus spp. in how the carrion niche is partitioned.

Rhynchophorus palmarum, an invasive palm pest in San Diego County California, has killed thousands of Phoenix canariensis. Over July 2016 to December 2022, this study tracked the population phenology of R. palmarum. Trapping data, derived from the capture of 8,262 weevils, of which 65% were female, indicated strong and predictable seasonal patterns in adult weevil activity, with trap captures increasing after March, peaking in July, before declining steadily towards December. Approximately 80% of weevils were trapped between April and October. This finding has important implications for the timing of management practices. Frond pruning should be done over November to March when weevil flight activity is low, and prophylactic insecticide applications should be made in March and June prior to increased weevil flight activity in April and July. Temperature and day length were strongly correlated with weevil capture rates, while precipitation, wind speed, and relative humidity were not. In urban areas over a 7-year survey period, August 2016 to August 2023, palm mortality rates, based on observations of 521 palms, indicated that 68% were killed. Drone surveys of 637 wilding P. canariensis in the Sweetwater Reserve exhibited a 73% rate of mortality over August 2016 to August 2023. Strong cardinal effects were observed for palm mortality in urban areas with west and east quadrants exhibiting higher rates of mortality in comparison to palms in north and south quadrants. In urban areas, weevil killed palms were removed on average, after 400 days, at an estimated average cost of $2,861 per palm.

Fire is increasingly used as a management tool in temperate deciduous forests, but the effects of fire on arthropods in these systems remain unclear. Here, we used flight-intercept traps to sample beetle assemblages (Coleoptera) in portions of a temperate deciduous forest of eastern North America subjected to either a higher-severity burn, a lower-severity burn, or no burn. We collected beetles immediately following the burns and for up to 2 yr post-burn. Average (±SE) beetle abundance did not differ between the higher-severity (45 ± 13) and lower-severity (55 ± 26) burns but was 2× higher in the burned sites vs. the unburned site (25 ± 6). Likewise, traps in the 2 burned sites captured a similar number of beetle species (17 ± 0.5 and 15 ± 0.5, respectively), and more species than in the unburned site (12 ± 0.4). These patterns were consistent over time post-burn in all sites. Beetle composition also consistently differed between the burned and unburned sites; bark and ambrosia beetles (Curculionidae: Scolytinae) were the most abundant groups in the burned sites. Species turnover (beta diversity) was highest in the unburned site. Eleven species were associated with specific combinations of burn treatment and time post-burn. The results suggest that fire severity and time post-burn play key roles in structuring local beetle assemblages and that longer fire intervals (≥3 yr) are required to facilitate recovery. Measuring beetle responses to fire in temperate deciduous forests improves our understanding of the effects of disturbance-based management on local biodiversity.

Following the de-registration of lindane as a cereal crop seed treatment for wireworm control in North America, most of the research efforts to find replacements have focused on neonicotinoid, diamide, pyrethroid, phenyl pyrazole, and most recently, meta-diamide and isoxazoline insecticide classes. Although insecticides within these classes have been shown to provide cereal crop protection from wireworm damage, not all insecticides will significantly reduce wireworm populations in the field. To investigate this, we exposed wireworms (Agriotes obscurus L. and Agriotes lineatus L.) to wheat seeds treated with insecticides in the above insecticide classes in soil bioassays in the lab, with a focus on the newly developed meta-diamide broflanilide and the isoxazoline isocycloseram. Various wireworm behaviors (eg repellency) were observed in soil window studies for 3 h, and symptoms of toxicity were recorded upon wireworm removal at 24 h and again at 7 d. No repellency was recorded from seed treated with broflanilide, isocycloseram, thiamethoxam (neonicotinoid), cyantraniliprole (diamide), and fipronil (phenyl pyrazole), but moderate repellency occurred with the pyrethroid λ-cyhalothrin. After 24 h exposure, thiamethoxam, cyantraniliprole, and λ-cyhalothrin treatments had elicited only minor morbidity symptoms, which had mostly disappeared after 7 d. Broflanilide, isocycloseram, and fipronil treatments, however, progressed from initial minor morbidity symptoms to more irreversible morbidity symptoms after 7 d. These data and earlier lab and field trials explain why field populations of wireworms are reduced by broflanilide, isocycloseram, and fipronil treatments relative to neonicotinoid, diamide, and pyrethroid insecticides.